Geology and geochemistry of Zn-Pb(-Ge-Ag) deposits in the Sichuan-Yunnan-Guizhou Triangle area, China: A review and a new type

Abstract

Mississippi Valley Type (MVT)1 deposits represent the majority of carbonate-hosted Zn–Pb deposits globally. They typically form in an extensional tectonic setting along passive margins. However, studies on carbonate-hosted Zn–Pb deposits in the Sichuan–Yunnan–Guizhou Triangle area (SYGT) reveal differences in terms of the essential features of typical MVT deposits. We discuss the main features of these deposits, controlled by folds and faults, high-grade Zn–Pb ores and symbiotic or associated elements (i.e., abundant Ag and dispersed amounts of Ge, Ga, and Cd) of significant economic value. Based on a comparison of Pb-Zn deposits in SYGT and classical MVT deposits formed in an extensional tectonic setting, as well as a subsequent discussion on deposit classification, we propose that the Huize-style Zn–Pb deposits are a new deposit style, whose basic features can guide future ore exploration. We define the Huize-style deposits based on four factors: i) Hierarchical ore-controlling system of strike-slip fault-fold structures, ii) litho-facies associated with typical alternation and mineralisation, iii) ore-forming geochemical features revealed by typical mineral assemblages, mineralisation alteration zoning, fluid-inclusion, isotope geochemistry and metallogenic acid–alkali geochemical barriers, and iv) different prospecting methods to those typically used for MVT deposits. The Huize-style and typical MVT deposits constitute the carbonate-hosted non-magmatic epigenetic hydrothermal-type (CNHT) Zn–Pb deposits.

Carbonate-hosted Pb-Zn deposits in China: a review of the geological characteristics and genesis

“…We summarize the basic geological characteristics of the carbonate-hosted Pb-Zn deposits in the Yangtze and Cathaysia blocks, and the Himalayan-Tibetan orogen as below. Complementary reading of the Pb-Zn deposit geology can be found in several review paper (Zhou et al, Song et al, 2019;Han et al, 2023). Furthermore, a preliminary insight into the controls on the Pb-Zn mineralization in the different metallogenic belt is presented.…”

“…To date, more than 450 Zn-Pb deposits and occurrences have been identified in the SYG triangle, containing >2000Mt reserves of sulphide ore at grades of 10-35% Pb + Zn (Fig. 2B) (Han et al, 2023). Sulphide ores in the Pb-Zn deposits are in general characterized by high Zn+Pb grade with average >10 % and enrichment in Ag, Cu, Cd, Ge and Ga (Ye et al, 2011.…”

“…Sulphide ores in the Pb-Zn deposits are in general characterized by high Zn+Pb grade with average >10 % and enrichment in Ag, Cu, Cd, Ge and Ga (Ye et al, 2011. Among these deposits, the Huize Pb-Zn-(Ag-Ge) deposit, Daliangzi Pb-Zn-(Cd-Ge) deposit, Maozu Pb-Zn-(Ag-Ga) deposit, Maoping Pb-Zn deposit and Tianbaoshan Pb-Zn deposit are classified as being large Pb-Zn deposits with contained metal reserves of over 2Mt (Han et al, 2023). The geological characteristics of the Huize, Daliangzi and Maozu deposits are described in detail in the section below.…”

“…These faults were activated and reactivated during major tectonic events, together with the development of numerous secondary NE-and NW-trending faults and fold-and-thrust belts in this area (Xu et al, 2020;Han et al, 2023, and references therein). In general, the NWW-trending extensional faults and NE-and NWtrending thrust faults and folds control most of the known leadzinc deposits in the SYG triangle (Han et al, 2023).…”